In the era of global green energy development, the use of energy storage batteries has become increasingly widespread. Currently, among the widely used cylindrical lithium-ion batteries in the market, there are 18650 batteries and 21700 batteries. The 21700 battery was initially co-developed by Panasonic and Tesla, and it was touted as having the highest energy density and lowest cost at the time, making it more affordable.
The 21700 lithium-ion battery is an upgraded version of the 18650 battery, named based on its size specifications. The “21” denotes a diameter of 21mm, “70” indicates a height of 70mm, and the “0” signifies its cylindrical shape.
Initially, 21700 lithium batteries were primarily used in new energy vehicles, providing sufficient power to drive the vehicles, thus enhancing their range and performance. Over time, their applications have expanded to include a wide range of devices such as chargers, electronic cigarettes, flashlights, medical equipment, handheld gimbals, and even solar energy storage systems to store energy generated by solar panels. 21700 batteries are also used in power tools and other high-power devices, as they can supply the high power required by such equipment.
The advantages of 21700 batteries include a higher energy density compared to 18650 batteries. According to information released by Tesla, the energy density of the 21700 battery system is approximately 300Wh/kg under current conditions, which is about 20% higher than the 250Wh/kg of the original 18650 battery system. However, in practice, 21700 batteries cannot completely replace 18650 batteries, as 18650 batteries have a wide range of applications beyond electric vehicles, including consumer electronics, drones, and power tools, and switching to 21700 batteries would likely increase costs.
21700 batteries are high-energy-density power cells with a high discharge rate, making them suitable for applications like electric vehicles and power drills. The increase in energy density in 21700 batteries is achieved not through changes in size but by reducing cobalt content and increasing nickel content. Nickel, being a more reactive metal, boosts energy density, resulting in improved battery performance and greater reliability and stability when assembled into battery packs.
While the development of 21700 batteries has been rapid, there is fierce competition among various types of batteries. In large-scale applications, 21700 cells face competition from prismatic batteries and pouch cells. Therefore, manufacturers of 21700 batteries need to continuously innovate in materials and improve cell performance to enhance the competitiveness of 21700 batteries and expand their range of applications.
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